com.google.gwt.json.client.JSONNull Maven / Gradle / Ivy
/*
* Copyright 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.json.client;
import com.google.gwt.core.client.JavaScriptObject;
/**
* Represents the JSON null value.
*/
public class JSONNull extends JSONValue {
private static final JSONNull instance = new JSONNull();
/**
* Returns the singleton null-valued JSON object.
*/
public static JSONNull getInstance() {
return instance;
}
/**
* Called from {@link #getUnwrapper()}.
*/
private static JavaScriptObject unwrap() {
return null;
}
/**
* There should only be one null value.
*/
private JSONNull() {
}
/**
* Returns this, as this is a JSONNull.
*/
@Override
public JSONNull isNull() {
// Workaround for https://code.google.com/p/google-web-toolkit/issues/detail?id=8139
if (this != instance) {
return null;
}
return this;
}
/**
* Returns "null" to allow for formatting null values.
*/
@Override
public String toString() {
return "null";
}
@Override
native JavaScriptObject getUnwrapper() /*-{
return @com.google.gwt.json.client.JSONNull::unwrap();
}-*/;
}